如何迭代命名元组列表，按键值过滤分组得到匹配的音频文件组合

现有3个存储命名元组的列表，分别对应鼓轨、旋律轨、贝斯轨的音频信息，代码如下：

drumlist = [drums( title='99_drumtrack_1.wav', bpm='99'),
drums( title='95_drumtrack_2.wav', bpm='95'),
drums( title='93_drumtrack_3.wav', bpm='93'),
#etc...
]

melodylist = [melody( title='99_Abmin_melodytrack_1.wav', bpm='99', key='Abmin'),
melody( title='95_Bbmin_melodytrack_2.wav', bpm='95' ,key='Bbmin'),
melody(title='93_Fmaj_melodytrack_3.wav', bpm='93' , key='Fmaj'),
melody(title='92_Gmaj_melodytrack_4.wav', bpm='92' , key='Gmaj')
#etc...
]

basslist = [bass( title='99_Abmin_basstrack_1.wav', bpm='99', key='Abmin'),
bass(title='95_Bbmin_basstrack_2.wav', bpm='95', key='Bbmin'),
bass(title='93_Fmaj_basstrack_3.wav', bpm='93', key='Fmaj')
#etc...
]

需要实现的匹配规则：按bpm匹配，同时旋律、贝斯的key（调性）一致的三个文件分为一组，每组生成sound1（鼓文件名）、sound2（旋律文件名）、sound3（贝斯文件名）三个变量供后续处理，期望输出示例如下：

#interation 1
sound1 = 99_drumtrack_1.wav
sound2 = 99_Abmin_melodytrack_1.wav #KEYNOTE Abmin key for melody matches Abmin key for bass
sound3 = 99_Abmin_basstrack_1.wav #KEYNOTE Abmin key for bass matches Abmin key for melody
#use sound1, sound2 & sound3 variables further

#interation 2
sound1 = 95_drumtrack_2.wav
sound2 = 95_Bbmin_melodytrack_2.wav
sound3 = 95_Bbmin_basstrack_2.wav
#use sound1, sound2 & sound3 variables further

#etc...

当前用嵌套for循环实现缩进层级过多，希望得到更简洁高效的实现方案。

推荐用索引映射的方案，完全避免多层嵌套循环，逻辑清晰且效率更高：

# 1. 先构建两个索引字典，把查询复杂度降到O(1)
# 鼓轨按bpm做索引，key为bpm值，value为对应鼓轨文件名
drum_index = {d.bpm: d.title for d in drumlist}
# 贝斯轨按 (bpm, key) 复合条件做索引，key为(bpm, key)元组，value为贝斯文件名
bass_index = {(b.bpm, b.key): b.title for b in basslist}

# 2. 直接遍历旋律轨匹配即可
for idx, melo in enumerate(melodylist, 1):
    # 同时匹配到对应bpm的鼓、对应bpm+key的贝斯才输出
    if melo.bpm in drum_index and (melo.bpm, melo.key) in bass_index:
        sound1 = drum_index[melo.bpm]
        sound2 = melo.title
        sound3 = bass_index[(melo.bpm, melo.key)]
        # 此处直接调用三个变量做后续业务处理即可
        print(f"# iteration {idx}")
        print(f"sound1 = {sound1}")
        print(f"sound2 = {sound2} #KEYNOTE {melo.key} key for melody matches {melo.key} key for bass")
        print(f"sound3 = {sound3} #KEYNOTE {melo.key} key for bass matches {melo.key} key for melody")
        print("# use sound1, sound2 & sound3 variables further\n")

如果存在同个bpm对应多个鼓轨的场景，只需把鼓索引的value改为列表存储即可，调整代码如下：

from collections import defaultdict
drum_index = defaultdict(list)
for d in drumlist:
    drum_index[d.bpm].append(d.title)

# 匹配时遍历对应bpm下的所有鼓轨即可
for idx, melo in enumerate(melodylist, 1):
    if melo.bpm in drum_index and (melo.bpm, melo.key) in bass_index:
        for drum_title in drum_index[melo.bpm]:
            sound1 = drum_title
            sound2 = melo.title
            sound3 = bass_index[(melo.bpm, melo.key)]
            # 后续业务逻辑

内容的提问来源于stack exchange，提问作者Andrew Jackson